Radix Rehmanniae Praeparata (熟地黄) is mainly used to nourish yin and tonify blood (nourishing the blood in the body), benefit the essence and fill in the marrow. It can be used to treat yin deficiency and blood deficiency, lumbar and knee impotence, labor and coughing, spermatorrhea, leakage of spermatozoa, menstrual irregularities, and other diseases. Radix Rehmanniae Praeparata is sweet in taste and slightly warm in nature, with the effects of nourishing yin and tonifying blood, benefiting the essence and filling in the marrow, and can be used to treat yin deficiency and blood deficiency, lumbar and knee impotence, coughing and bone vaporization, spermatorrhea, leakage, menstrual disorders, thirst, urination, deafness, and dimness of the eyes. Although Radix Rehmanniae Praeparata has a good effect of nourishing Yin and tonifying Blood, it is not suitable for people with stagnation of Qi and phlegm, distension and pain in the epigastrium (abdomen), and loose stools (scanty and unshaped feces). It should not be taken randomly in daily life, and should be taken under the guidance of a doctor to avoid the adverse effects of taking medicines randomly.